The present invention relates to a photosensitive laser beam receiver circuit. Specifically, the present invention relates to a laser beam receiver circuit operative to enable the calculation of a position of a laser beam relative to an array of photosensitive cells.
Rotating laser beams are commonly used in the fields of civil engineering, construction, agriculture, and surveying to establish a reference plane of light. U.S. Pat. No. 5,033,847, issued Jul. 23, 1991, illustrates a laser transmitter which provides such a rotating reference beam. As is further illustrated in U.S. Pat. No. 3,588,249, issued Jun. 28, 1971, a photosensitive laser beam receiver is frequently used to monitor the position of the reference plane of light.
A conventional photosensitive laser beam receiver circuit described in U.S. Pat. No. 4,693,598, issued Sep. 15, 1987, employs a plurality of photodiodes disposed in a row and individually connected to a corresponding light emitting diode through separate amplifier circuits. When the laser beam impinges on one of the photodiodes, the corresponding light emitting diode is illuminated. An operator may then determine the relative position of the measuring receiver with respect to the radiation plane from the position of the respective light emitting diode along the light emitting diode display.
The conventional laser beam receiver circuit has a number of shortcomings, however, which limit its utility in many practical applications. Specifically, the degree of precision required in some linear position measurement applications has exceeded the degree of precision available in conventional receiver circuits. In addition, many surveying and engineering applications require laser beam receivers of significant vertical dimension, e.g., approximately 10 inches (25.4 cm) from a lowermost photosensor to an uppermost photosensor. These significant dimensions require a corresponding significant number of photosensors and, if the conventional receiver circuit is to be employed, a corresponding significant number of amplifiers. Manufacturing costs and circuit power requirements increase prohibitively with increasing numbers of amplifiers and associated circuitry.
Accordingly, there is a need for a laser beam receiver circuit of improved precision wherein a significant number of photosensors may be coupled to a reduced number of signal amplifiers and associated circuitry such that manufacturing costs and circuit power requirements are maintained at a practical level.